Means for obtaining the polar diagram of an alternating-current wave



April 28, 1925. 1,535,329

. J. T. MEICGREGOR-MORRIS ET AL MEANS FOR OBTAINING THE POLAR DIAGRAM OFAN ALTERNATING CURRENT WAVE Filed Feb. 5, 1923 INVENTORS J. T.MacGREGOR-MbRE 1s F.'R.F.RAMSAY,

By the i7 Afutorncys,

Patented Apr. 28, 1925.

warren stares 1,535,329 PATENT QFFHCE. 3

JOHN TURNER MAcGREGOR-MORRIS AND FRANK RAYMOND FABER RAMSA'Y, OF

LONDON,

MEANS FOR- OBTAINING THE POLAR- DIAGRAM OF AN ALTERNATING-CURRENT WAVE.

Application filed February 5, 1928. Serial No. 617,118.

To all whom, it may concern:

Be it known that we, JOHN TURNER Mac- Gnncon-Monms, a'subject of theKing of Great Britain, residing at 3, Lyndhurst Road, Hampstead, London,England, and FRANK RAYMOND FABER RAMSAY, a subject of the King of GreatBritain, residing at East London College, Mile End Road, London,England, have invented new and useful Improved Means for Obtaining thePolar Diagram of an Alternating-Current \Vave, of which the following isa specification.

The object of this invention is to provide simpler and less costlyapparatus than has hitherto been known for producing the polar diagramof an alternating current wave.

It is known that -if the cathode ray in a cathode tube be subjected tothe action of an electromagnetic or an electrostatic field it isdeflected and that it the rays be allowed to fall upon a fluorescentscreen in the tube the portion of the screen upon which they fallbecomes luminous, so that if the field is due to an alternating currentthe trace on the screen is a straight line.

According to this invention we pass the current wave whose polar diagramit is desired to obtain through a device by means of which the cathoderays will be deflected and we cause this device torotate uniformlyaround the axis of the tube at such a speed that it will complete onerevolution in each cycle of the current, with the result that thediagram due to the negative portion of each cycle will be superimposedupon the diagram due to the positive portion, and thus a stable orpersistentdiagram will be visible upon the screen. This diagram may beviewed directly or may be photographed if a permanent record isrequired.

Our invention is illustrated by the accompanying drawing, Figure 1 ofwhich is a vertical longitudinal section while Figure 2 is a crosssection on the line aa, Figure 1. Fi re 3 shows the fluorescent screenand F lgure 4 is a diagram of the connections. Figure 5 shows amodification. I A is a cathode ray tube having in it a cathode B and atubular anode C. Surrounding the stem of the tube is a sleeve D on hichis mounted the armature of an electric motor E and also a c linder F ofinsulating material. In this cyhnder are two Y coils G, G, arrangedopposite to one am other and also two plates H, H, also arrangedopposite to one another and at right angles to the COllS G, G. Theplates and COllS are connected to slip rings I. Beyond the cylinder F isa sleeve D, the two sleeves rotate around the tube at such a speed thatthey complete one revolution in each cycle of the current.

It the current have a pure sine form the .cathode ray will form on thefluorescent screen J a circle, and in order that it may be easilyascertained if the current is of pure sine form we preferably mark uponthe screen as shown in Figure 3 a number of circles, all having onecommon point in their circumferences, by comparison with which thecircular form of the diagram may be ascertained.

It is necessarv that there be some provision for focussing the rays suchthat they only strike a .very small portion of the screen at any oneinstant.

Preferably we provide means such as a permanent magnet M for impartingto the cathode rays an initial deflection, so that the diagram on thescreen may be brought to the desired position.

If it is desired to obtain the voltage diagram of the alternatingcurrent Wave, the current Wave is led to the sliprings I so that thepotential will be applied to the two plates H instead of the currentbeing led through the coils G.

Should it be desired to obtain simultaneously a diagram of the currentand'of the voltage, the slip rings and connections may be arranged asshown in Figure 4. On an examination of this figure it will be seen thatduring half a revolution the current will pass via the brushes L andslip rings I through the coils G and through the load represented by Kin series with the coils G but that for the other half of the revolutionthe potential will be applied to the "plates H H, which are connected inparallel witi the load. Thus one half cycle of the alternating currentwill 've a current curve while the other hal cycle will give a voltagecurve, and as these two curves succeed one another in rapid successionboth curves will appear to be visible together on the screen.

In place of the plates H, H, two fine wire coils h, h, (see Figure 5) inseries with a high non-inductive resistance R may be used if desired andthese coils may be wound on the same core as the coils G, G.

The motor E may be employed to generate the voltage necessary for theproduction of the cathode ray. I

What we claim is 1. The combination with a cathode ray tube having afluorescent screen of a device adapted to deflect the cathode rays,means for applying an alternating current wave to that device and meansfor rotating the device in synchronism with the wave.

2. The combination with a cathode'ray tube having a fluorescent screen,of two coils arranged one on each side of the stem of the tube, meansfor applying an alternating current wave to the coils and means forrotating the coils around said stem in synchronism with the wave.

3. The combination with a cathode ray tube having a fluorescent screen,of an electric motor the armature of which can rot-ate about the axis ofthe stem of the tube and a device fast with the armature and adapted todeflectv the cathode rays.

4. The combination with a cathode ray tube having a fluorescent screen,of an electric motor the armature of which can rotate about the axis ofthe stem of the tube and two coils arranged one on each side of the stemof the tube and fast with said armature.

5. The combination with a cathode ray tube having a fluorescent screen,of means for producing around the path of the cathode rays anelectromagnetic field due to an alternating current wave andmeans forrotating said field producing means around said path once for each cycleof the wave.

6. The combination with a cathode ray tube having a fluorescent screen,of means for producing around the path of the cathode rays either anelectromagnetic or an electrostatic field due to an alternating currentwave and means for rotating said field producing means around said pathonce for each cycle of the wave.

7. The, combination with a cathode ray tube having a fluorescent screen,of two coils arranged one on each side of the stem of the tube, twoplates also arranged one on each side of the stem of'the tube, means forapplying an alternating current wave to the coils, and to the plates,and means for rotating the coils and plates around said stem insynchronism with the wave.

8. Thecombination with a cathode ray tube having a fluorescent screen,of an electric motor the armature of which can rotate about the axis ofthe stem of the tube, two coils arranged one on each side of the stem ofthe tube, and two plates also arranged one on each side of the stem ofthe tube, the coils and plates being fast with said armature.

9. The combination of a cathode ray tube comprising a stem having in ita cathode and a tubular anode, a fluorescent screen within the tube, anelectric motor the armature of which is hollow and surrounds said stem,two coils arranged one on each side of said stem and fast with saidarmature and means for passing an alternating current through the motorand the coils.

In testimony that we claim the foregoing as our invention we have signedour names this nineteenth day of January, 1923.

JOHN TURNER MacGREGOR-MORRIS..

FRANK RAYMOND FABER RAMSAY.

